Final answer:
Aristotle defines virtue as the mean between two extremes, such as bravery being a balance between cowardice and rashness. Virtue is fostered through habituation and is an objective good that is tied to fulfilling the unique function or purpose of beings, with rationality being the human function leading to human excellence.
Step-by-step explanation:
Aristotle posits that virtue is the mean between extremes of deficiency and excess--a balance struck within our actions and feelings. This concept is also known as the Doctrine of the Mean and is integral to Aristotle's ethical framework. Virtue is about finding this equilibrium in varied facets of life. Bravery, for example, is a virtue that lies between the deficiency of cowardice and the excess of rashness, indicating that a brave individual has the correct amount of fear and confidence.
Aristotle's virtue ethics is encapsulated in his notion that habituation plays a key role in ethical development. Individuals become virtuous by diligently practicing virtuous deeds, hence creating a habitual inclination towards virtuous actions in life's many contexts. According to Aristotle, virtues are not innate but are developed through consistent practice and the cultivation of character.
In essence, virtue, for Aristotle, is therefore an objective good closely tied to the unique function or purpose of a thing--a sharp knife is good because cutting is its purpose. Similarly, a human's function is rationality, and as such, cultivating a rational character is equivalent to achieving human excellence or virtue.